In the following species, how many species have the same magnetic moment? (i) Cr\(^{2+}\) (ii) Mn\(^{3+}\) (iii) Ni\(^{2+}\) (iv) Sc\(^{2+}\) (v) Zn\(^{2+}\) (vi) V\(^{3+}\) (vii) Ti\(^{4+}\)
A particle is moving in a straight line. The variation of position $ x $ as a function of time $ t $ is given as: $ x = t^3 - 6t^2 + 20t + 15 $. The velocity of the body when its acceleration becomes zero is: